Recent advances in telephony have made possible full duplex audio communication in conjunction with full duplex video communication. However, many disadvantages are present when implementing video telephony over existing telephone lines. Chief among the problems is that of unacceptable image quality. The images do not have the requisite clarity and sharpness to which consumers have become accustomed. Additionally, motion of the video frames is frequently jittery and synchronism between the motion of the video and the corresponding audio is lost.
There are several high and medium speed transmission technologies currently in use that are capable of carrying acceptable quality digital video telephone (hereinafter referred to as “videophone”) signals. Examples of these transmission media include local area networks (LAN) or wide area networks (WAN), which have been used for video conferencing and the like. However, few consumers have access to such networks except via modems that are too slow to accommodate videophone signals in an acceptable manner, i.e., without delays and jitter, thereby failing to alleviate the problems with conventional videophone over existing telephone networks. Additional means for connecting consumers and businesses alike to videophone technology are becoming increasingly available. Among these new technologies are various forms of digital subscriber lines (XDSL), ISDN, and subscriber networks known as switched digital video or fiber-to-the-curb (FTTC).
Many of the above methods for providing videophone services to consumers and businesses suffers from the disadvantage that a new infrastructure must be built at great, almost prohibitive, cost. Furthermore, none of the above-mentioned alternatives has the ability to carry existing analog television signals. In order to overcome these and numerous other disadvantages in the transport of videophone signals, what is needed is a system that is capable of utilizing existing infrastructure, while providing the speed and bandwidth capacity required to realize acceptable videophone signals, thereby avoiding the expense of new infrastructure and providing greater access to videophone services.